Standardized assessments of binding, neutralization, ADCC, and ADCVl effector activities of antibodies elicited by candidate HlV-1 Env immunogens are critical for informing HIV-1 vaccine design. Core B (Immune Monitoring Core) will provide standardized and validated GCLP humoral immune monitoring assay services for evaluating antibody responses elicited by Ad26/Ad26 and A26/MVA vector regimens with and without an Env gp140 trimer protein boost. We further propose to utilize additional assays for mapping the epitope specificities of NAb generated by these unique vaccine regimens. These services will provide critical support for Projects 1 and 2 by providing data that will help guide immunogen design and strategies for vaccine formulation and delivery.! We propose the following Specific Aims for Core B: 1. We will assess Env-specific antibody responses in subjects immunized with candidate HlV-1 Env immunogens for binding, neutralization, ADCC, and ADCVl effector activities. 2. We will utilize multiple assay formats for mapping the epitope specificities of antibodies elicited by vaccine regimens tested in Projects 1 and 2.